scholarly journals The mechanism of the hydrogen-oxygen reaction V. The reaction in vessels coated with alkali iodides

1946 ◽  
Vol 186 (1007) ◽  
pp. 469-472 ◽  
Keyword(s):  
Gas Phase ◽  
Reaction Rate ◽  
Surface Reaction ◽  
Indirect Evidence ◽  
Alkali Halides ◽  
Normal Reaction ◽  
Mode Of Operation ◽  
Reduced Rate ◽  
Halide Salts ◽  
Mechanism Of The Reaction

Previous work on the hydrogen-oxygen combination in vessels coated with alkali halides showed that with the iodides the temperature dependence of the reaction rate is abnormal. In iodide-coated vessels the whole mechanism of the reaction is now shown to be different: the greatly reduced rate is independent of [H 2 ], proportional to a + b [O 2 ] and independent of added nitrogen, all in sharp contrast with what is found in chloride-coated vessels. The normal reaction is thought to be completely suppressed by minute amounts of iodine liber­ated into the gas phase, a residual surface reaction being measured. The chemical actions which must be assumed to occur between the iodide and the gases provide indirect evidence for the probable mode of operation of the other halide salts in controlling the hydrogen-oxygen combination.

Energy transfer through a dissociated diatomic gas in Couette flow

1958 ◽  
Vol 4 (5) ◽  
pp. 441-465 ◽  
Author(s):  
John F. Clarke
Keyword(s):  
Energy Transfer ◽  
Gas Phase ◽  
Couette Flow ◽  
Chemical Reaction ◽  
Chemical Equilibrium ◽  
Reaction Rate ◽  
Surface Reaction ◽  
Rate Equations ◽  
Equilibrium Flow ◽  
Diatomic Gas

The transfer of energy through a dissociated diatomic gas in Couette flow is considered, taking oxygen as a numerical example. The two extremes of chemical equilibrium flow and chemically frozen flow are dealt with in detail, and it is shown that the surface reaction rate is of prime importance in the latter case. The chemical rate equations in the gas phase are used to estimate the probable chemical state of the gas mixture, this being deduced from the ratio of a characteristic chemical reaction time to a characteristic time for atom diffusion across the layer. The influence of the surface reaction appears to spread outwards through the flow from the wall as gas-phase chemical reaction times decrease. For practical values of the surface reaction rate on a metallic wall, the energy transfer rate may be significantly lower in chemically frozen flow than in chemical equilibrium flow under otherwise similar circumstances.Similar phenomena to those discussed will arise in the more complicated case of boundary layer flows, so that a treatment of the simpler type of shear layer represented by Couette flow may be of some value in assessing the relative importance of the various parameters.

A polycentric growth model of gallium arsenide epitaxial layers from the gas phase with simultaneous diffusion, adsorption and chemical reaction

1988 ◽  
Vol 53 (12) ◽  
pp. 2995-3013
Author(s):  
Emerich Erdös ◽  
Jindřich Leitner ◽  
Petr Voňka ◽  
Josef Stejskal ◽  
Přemysl Klíma
Keyword(s):  
Growth Rate ◽  
Gallium Arsenide ◽  
Epitaxial Growth ◽  
Gas Phase ◽  
Surface Reaction ◽  
Quantitative Description ◽  
The Other ◽  
Rate Equations ◽  
Impact Interaction ◽  
Partial Pressures

For a quantitative description of the epitaxial growth rate of gallium arsenide, two models are proposed including two rate controlling steps, namely the diffusion of components in the gas phase and the surface reaction. In the models considered, the surface reaction involves a reaction triple - or quadruple centre. In both models three mechanisms are considered which differ one from the other by different adsorption - and impact interaction of reacting particles. In every of the six cases, the pertinent rate equations were derived, and the models have been confronted with the experimentally found dependences of the growth rate on partial pressures of components in the feed. The results are discussed with regard to the plausibility of individual mechanisms and of both models, and also with respect to their applicability and the direction of further investigations.

Ab Initio Computation of Thermochemistry and Kinetics in the Oxidation of Gas Phase Silicon Species

1992 ◽  
Vol 282 ◽  
Author(s):  
Michael R. Zachariah ◽  
Wing Tsang
Keyword(s):  
Ab Initio ◽  
Gas Phase ◽  
Energy Barrier ◽  
Reaction Rate ◽  
Rate Theory ◽  
Molecular Orbital Calculations ◽  
Activation Energy Barrier ◽  
Ab Initio Computation ◽  
Oxygen Donor ◽  
Reaction Rate Theory

ABSTRACTAb initio molecular orbital calculations coupled to RRKM reaction rate theory have been conducted on some important reactions involved in the oxidation of silane in a high-temperature/high H2O environment. The results indicate thatH2O acts as an oxygen donor to SiH2 to form H3SiOH or SiH2O. Subsequent reactions involve the formation of (HSiOOH, H2Si(OH)2,:Si(OH)2 or SiO). In turn SiO polymerizes into planar rings, without an activation energy barrier. A list of calculated thermochemical data are also presented for a number of equilibrium species.

Reaction rate constant of SO3+ NH3in the gas phase

1990 ◽  
Vol 95 (D9) ◽  
pp. 13981 ◽  
Author(s):  
Gaunlin Shen ◽  
Masako Suto ◽  
L. C. Lee
Keyword(s):  
Gas Phase ◽  
Rate Constant ◽  
Reaction Rate ◽  
Reaction Rate Constant

First accurate experimental study of Mu reactivity from a state-selected reactant in the gas phase: the Mu + H2{1} reaction rate at 300 K

2015 ◽  
Vol 48 (4) ◽  
pp. 045204 ◽  
Author(s):  
Pavel Bakule ◽  
Oleksandr Sukhorukov ◽  
Katsuhiko Ishida ◽  
Francis Pratt ◽  
Donald Fleming ◽  
...  
Keyword(s):  
Experimental Study ◽  
Gas Phase ◽  
Reaction Rate
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